This invention relates to a capsule product containing a combination of aspirin as the significant active analgesic ingredient and an alkaline material. For a long time, it has been appreciated that the coadministration of aspirin along with an alkaline material has certain distinct advantages. One of these is that the presence of the alkaline material serves to increase the rate at which the aspirin is absorbed into the bloodstream. A second benefit is that the alkaline material tends to decrease any irritation to the gastrointestinal mucosa that aspirin may cause in some subjects.
Although these are recognized benefits for the coadministration of aspirin and alkaline materials, the incorporation of these materials in a single dosage form has presented problems. Aspirin is hydrolyzed to salicylic acid by alkaline material when moisture is present with the result that some of its effectiveness as an analgesic is reduced. In the case of tabletted products, efforts have been made to stabilize these products by forming the tablets in two layers, one layer containing the aspirin and the other layer containing the alkaline material. This has proven to be relatively successful in providing a stable tablet i.e. one in which the aspirin is not readily hydrolyzed.
In the case of people who have difficulty swallowing tablets, it is also desirable to be able to administer aspirin-containing products in the form of a capsule which is generally considered to be easier to swallow than tablets. This is particularly the case when the dosage of aspirin in each dosage form is relatively large. Moreover, aspirin-containing tablets sometimes dissolve in the mouth leaving a taste that most people find objectionable. This is generally avoided when aspirin-containing products are administered in a capsule.
Efforts have been made to prepare aspirin-containing products commingled with alkaline materials in a capsule to obtain the benefits from this mode of administration. However, when the aspirin and alkaline materials were mixed together in the form of granules or powders and this mix was used to load the capsules, the resulting products did not have the requisite stability due to the presence of moisture and the intimate contact between the aspirin and the alkaline material.